1. Field of the Invention
The invention relates to coded cooperative networking; in an aspect of the invention, not intended to be limiting in any way, signals from multiple wireless sources are jointly coded and decoded using multiple wireless receivers, with the effect of improved robustness to channel fades and reduced penalty in bandwidth utilization.
2. Related Art
In communication systems, one known problem is that receivers sometimes receive distorted versions of signals sent by senders. In wireless communication, this can occur because of fading, that is, substantial reduction in the received strength or SNR (signal to noise ratio) of the incoming signal or a portion of its frequencies.
One known solution to fading is called “diversity,” in which the same data is sent using separate times, separate frequencies, or separate antennas. While this known solution reduces the effect of fading, it comes with a price: additional bandwidth use that might otherwise have been used for communication capacity. Moreover, in many wireless systems these diversity approaches are relatively inefficient, such as in the event that the maximum delay and bandwidth allowed by the system are relatively small, compared to restrictions imposed by the fading process coherence time and bandwidth.
A second known solution is called “cooperative diversity,” in which transmission from a sender to its receivers is received, decoded, and retransmitted by more than one intermediate relay station; with the effect that fading from the sender to its receivers is at least partially overcome. While this known solution further reduces the effect of fading, it still comes with the same price: additional bandwidth use that might otherwise have been used for communication capacity.
Another known technique, used in switching networks, sometimes called “network coding”, is performed in a switching network in which a digital message packet might be sent along multiple pathways from a source to a destination. While this technique improves the reliability of communication, it involves a switching network and not a broadcast network, it involves digital data and not analog signal information, and it involves multiple deliveries of the same data and no joint protective code.
Accordingly, it would be advantageous to provide coding and decoding techniques, methods and systems, not subject to drawbacks of the known art.